Base type range finder for medium ranges and short distances



Nov. 24, 1942. x F. w. GEHRKE 2,303,207

BASE TYPE RANGE FINDER FOR MEDIUM RANGES AND SHORT DISTANCES Filed Oct. 11. 1940 v' wim FRIEDRICH *WILHELM GEHRKE ATTORNEYS Patented Nov. 24, 1942 UNITED f STATES PATENT om e azosaor BASE ms RANGE man FOB MEDIUM moss AND snon'r DISTANCES Friedrich Wilhelm Gehrke, Munich. Germany, as-

signor to General Aniline a Film Corporation, New York, N. Y., a corporation of Delaware Application October .11, 1940,-Serial No. 360,732

r In Germany October 18,1939

ZClaiins. (or. 88-21:)

-This invention relates to a range finder, particularly to a base type range finder for measuring medium ranges and very short distances.

One of its objects is a process of measuring ranges.

Another object is a range finder.

Still another object is .a range finder for measuring small distances, especially distances below one meter.

FllIthel' '0bj6CtS will be seen from the accompanying drawing and detailed specification.

The present invention relates to a symmetric base type range finder which is'to be used espedaily for photographic cameras and which'serves both for the determination .of the usual distances also for the exact determination of distances below one meter. In order to measure the distance of very close objects, it has previously been proposed to employ additional lenses which at a defi- I nite very small distance of the object bring the.

\ two separate images into exact registry with each other. This method of determining the range, however, has the disadvantage of the additional lenses. To put these lenses on and to take them off again when changing from near to distant pictures and vice versa makes the handling of.

v such a range finder rather difficult.

7 According, to the'present invention it has been proposed to render the lens-wedges situated in front of the light entrance of the base type range finder displaceable successively parallel to the base of the range finder, in order to adjust the range-finder to medium and close ranges. Preferably both lens-wedges are moved in succession by the same adjusting device. The arms of the lens-wedgesare held by means of a spring, in firm contact with two control-disc-camswhich are mounted on the axis/of the adjusting device. One control-disc-cam serves for the displacement of one lens-wedge, in order to adjust ranges from 40 infinity to one meter, the other disc-cam adjusts the second lens-wedge for ranges below one meter, for example 50 cm. and 25 cm. The adjustment can be accomplished gradually or in steps.

The invention-is illustrated diagrammatically.

and by way of example on the accompanying drawing, in which Figure l is a plane view of a symmetrical range finder the cover plate being removed.

Figure 2 is also a plane view of a range finder the adjusting device being removed. The range finder is adjusted to very close objects.

Figure 3 is a single view of the two controldisc-cams with twoadjacent levers of contact.

Figure 4 is'a section of the view finder on line TIL-III of Figure 1. v

The light rays reflected from the object to be.

photographed penetrate through the lens-wedges l and 2 into the prisms 3 and 4, the latter forming the base of the range finder, and are thrown.

into' the eye of the observer by the eye-piece. 5 after being reflected twice. Whereas in such base type range finders only one lens element was movably arranged hithereto, the other one being I stationary, according tothe present invention both lens-wedges I and 2 -are rendered displaceable in succession parallel to the base of .the prisms 3 and 4, in order to deviate the light beams in various ways. Th two supports of the lens-wedges i and 2 contact the disc-cams 8 and Sthrough the contacting arms 6 and 1. These arms 6 and l are pressed by a spring to onto the disc-cams 8 and 9. The disc-cams fl'and care rigidly mounted onto the-squared portion Ila of the axis ll of the adjusting device l2. By means of the adjusting device I; it is possible to adjust the range finder to medium ranges or very close ranges.

along on the disc-cam 9does not change its po- Whereas the contacting arm 6 sliding sition when the adjusting device is. adjusted from infinity to one meter, since the portion of disccam 9 then in contact therewith is of circular shape (seen in counterclockwise direction), it is readily lifted up when the adjusting device is adjusted to ranges below one meter (see Figure j 3) thus displacing the lens-wedge I. The disccam 8 is so shaped that it displaces the contacting lever l and therewith the lens element 2 at distances from infinity down to one meter. At

distances, below one meter the lever is not. moved.

The disc-(:am-t is therefore (seen in counterclockwise direction) in the firstinstance eccentric to the axis ii, whereas it is centric to the axis ii later on.

What I claim is:

1. Symmetric base type range finder for meas uring medium ranges and very short distances v comprising two prisms forming the base of said.

range finder, two lens wedges disposed in front ;of said prisms, means for displacing said lens V wedges in succession parallel to saidbase and a single means for operating said first means.

' -2. Symmetric base type range finder for measuring medium ranges and very short distances comprising two prisms forming the base of said 

